We recommend the classification and map (Fig. 7) of Bailey (1976) to fill the need for regionalization inland. Bailey's classification of ecoregions is hierarchical. The upper four levels are domain (defined as including subcontinental areas of related climates), division (defined as including regional climate at the level of Köppen's [1931] types), province (defined as including broad vegetational types), and section (defined as including climax vegetation at the level of Küchler's [1964] types). On the map, the boundaries between the different levels are designated by lines of various widths and the sections are numbered with a four-digit code; digits 1 through 4 represent the first four levels in the hierarchy. The reader is referred to Bailey (1976, 1978) for detailed discussion and description of the units appearing on his map, reproduced in our Fig. 7.

The Bailey system terminates at the ocean, whereas the present wetland classification includes Marine and Estuarine habitats. Many workers have divided Marine and Estuarine realms into series of biogeographic provinces (e.g., U.S. Senate 1970; Ketchum 1972). These provinces differ somewhat in detail, but the broader concepts are similar. Figure 7 shows the distribution of 10 Marine and Estuarine provinces that we offer for North America.

• Arctic Province extends from the southern tip of Newfoundland (Avalon Peninsula), northward around Canada to the west coasts of the Arctic Ocean, Bering Sea, and Baffin and Labrador basins. It is characterized by the southern extension of floating ice, the 4°C summer isotherm, and Arctic biota.

• Acadian Province extends along the Northeast Atlantic Coast from the Avalon Peninsula to Cape Cod and is characterized by a well developed algal flora and boreal biota. The shoreline is heavily indented and frequently rocky. It has a large tidal range and is strongly influenced by the Labrador Current.

• Virginian Province extends along the Middle Atlantic Coast from Cape Cod to Cape Hatteras. The province is transitional between the Acadian and Carolinian Provinces. The biota is primarily temperate, but has some boreal representatives. The Labrador Current occasionally extends down to Cape Hatteras and winter temperatures may approach 4°C. The tidal range is moderate.

• Carolinian Province is situated along the South Atlantic Coast from Cape Hatteras to Cape Kennedy. It contains extensive marshes and well developed barrier islands. Waters are turbid and productive. The biota is temperate but has seasonal tropical elements. The Gulf Stream is the primary influence, and winter temperatures reach a minimum of 10°C; summer temperatures are tropical (in excess of 20°C). The tidal range is small to moderate.

• West Indian Province extends from Cape Kennedy to Cedar Key, Florida, and also includes the southern Gulf of Mexico, the Yucatan Peninsula, Central America, and the Caribbean Islands. The shoreland is usually low-lying limestone with calcareous sands and marls, except for volcanic islands. The biota is tropical and includes reef corals and mangroves. Minimum winter temperatures are about 20°C and the tidal range is small.

• Louisianian Province extends along the northern coast of the Gulf of Mexico from Cedar Key to Port Aransas, Texas. The characteristics of the province are similar to those of the Carolinian, reflecting the past submergence of the Florida Peninsula. The biota is primarily temperate and the tidal range is small.

• Californian Province extends along the Pacific Coast from Mexico northward to Cape Mendocino. The shoreland is strongly influenced by coastal mountains and the coasts are rocky. Freshwater runoff is limited. In the southern part volcanic sands are present; marshes and swamps are scarce throughout the province. The climate is Mediterranean and is influenced by the California Current. The biota is temperate, and includes well developed offshore kelp beds. The tidal range is moderate.

• Columbian Province extends along the northern Pacific Coast from Cape Mendocino to Vancouver Island. Mountainous shorelands with rocky foreshores are prevalent. Estuaries are strongly influenced by freshwater runoff. The biota is primarily temperate with some boreal components, and there are extensive algal communities. The province is influenced by both the Aleutian and California Currents. The tidal range is moderate to large.

• Fjord Province extends along the Pacific Coast from Vancouver Island to the southern tip of the Aleutian Islands. Precipitous mountains, deep estuaries (some with glaciers), and a heavily indented shoreline subject to winter icing are typical of the coast. The biota is boreal to subArctic. The province is influenced by the Aleutian and Japanese Currents, and the tidal range is large.

• Pacific Insular Province surrounds all the Hawaiian Islands. The coasts have precipitous mountains and wave action is stronger than in most of the other provinces. The biota is largely endemic and composed of tropical and subtropical forms. The tidal range is small.